The invention relates to active acoustic attenuation systems, and more particularly to a generalized multi-channel system.
The invention particularly arose during continuing development efforts relating to the subject matter shown and described in U.S. Pat. No. 4,815,139, incorporated herein by reference. The invention arose during continuing development efforts relating to the subject matter shown and described in U.S. Pat. Nos. 4,677,676, 4,677,677, 4,736,431, 4,837,834, and 4,987,598, and allowed applications Ser. No. 07/388,014, filed Jul. 31, 1989, and Ser. No. 07/464,337, filed Jan. 12, 1990, all incorporated herein by reference.
Active acoustic attenuation or noise control involves injecting a canceling acoustic wave to destructively interfere with and cancel an input acoustic wave. In an active acoustic attenuation system, the output acoustic wave is sensed with an error transducer such as a microphone which supplies an error signal to an adaptive filter control model which in turn supplies a correction signal to a canceling transducer such as a loudspeaker which injects an acoustic wave to destructively interfere with the input acoustic wave and cancel same such that the output acoustic wave or sound at the error microphone is zero or some other desired value.
The present invention provides a generalized multi-channel active acoustic attenuation system for attenuating complex sound fields in a duct, large or small, a room, a vehicle cab, or free space. The system may be used with multiple input microphones and/or multiple canceling loudspeakers and/or multiple error microphones, and includes a plurality of adaptive filter channel models, with each channel model being intraconnected to each of the remaining channel models and providing a generalized solution wherein the inputs and outputs of all channel models depend on the inputs and outputs of all other channel models.